How to fix lifetime bound not satisfied

Memory/Lifetimes
2026-04-17T12:05:42+00:00
Fix lifetime bound errors by adding explicit lifetime annotations to function signatures, structs, or traits to ensure references remain valid.

Add the missing lifetime annotation to the function signature or struct definition to satisfy the compiler's requirement that references live long enough.

fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
    if x.len() > y.len() { x } else { y }
}

If the error occurs in a struct, add the lifetime parameter to the struct definition and its impl block:

struct ImportantExcerpt<'a> {
    part: &'a str,
}

impl<'a> ImportantExcerpt<'a> {
    fn level(&self) -> i32 { 3 }
}

For trait bounds, ensure the lifetime is specified in the where clause or the trait definition:

trait Foo<'a> {
    fn method(&'a self);
}

If the error persists, verify that all references in the function or struct share the same lifetime parameter, or that the returned reference is tied to one of the input references.